Nice concept. Had some fun with this. I found the trick is to swap controls very often.
I must admit that the mouse controls were very nauseating due to the heavy smoothing. I'm not sure if this is intentional or not. But I would suggest to keeping with standards without the smoothing since that is what most people are used to.
Also, you could try indicating top/bottom control on the player character itself. Then the player doesn't have to pay attention to the corner of the screen.